The present invention relates to a coating composition which can be cured by an ultraviolet irradiating operation or the combination of the ultraviolet irradiating operation and a heating operation, and more particularly, to a composition with which a plastic molding or the other basic materials are coated and cured to form a protective film which is of improved surface hardness, scratch resistance and weather resistance.
Since the plastic molding is generally low in hardness, and inferior in abrasion resistance and scratch resistance, the molding is easily scratched and thus its transparency deteriorates. Among the plastic components used in electric products, containers and covers for electric cookers are scratched in use or when washed with a steel or nylon scrubbing-brush or the like, thus ruining their appearance and ability to be cleaned.
Furthermore, items such as transparent panels or covers for acoustic products are likely to be scratched during use. Accordingly, there is much room for improvement of these plastic components.
Among conventional protective coating compositions having the uses described above, there may be mentioned those containing organic silicone compounds, melamine compounds, etc. for application to the surface of base materials such as plastic moldings, etc. thereby to form a cured film. However, none of these known coating compositions can provide a pencil hardness of 7H or more.
In addition, these conventional coating compositions are inferior in weather resistance and abrasion resistance, thus providing unsatisfactory results. For example, one coating composition with good abrasion resistance forms a fragile protective film and is easy to crack, while crack prevention results in inferior abrasion and scratch resistance. Also, these known compositions are of the heat curing type, wherein a longer time is required to cure the compositions, and the coated compositions may be deformed and deteriorated due to the heating operation. Moreover, stable films of satisfactory hardness have not been obtained. Additionally, the pot life of these conventional compositions is often too short.
Accordingly, an object of the present invention is to provide a coating composition of such characteristics as described hereinabove which can eliminate the disadvantages inherent in the conventional ones.